Multi-pole circuit breakers



Feb. 2, 1960 Filed July 3, 1957 P. s. MARTIN 2,923,795 MULTI-POLE CIRCUIT BREAKERS 3 Sheets-Sheet l INVENTOR Feb. 2, 1960 P. s; MARTIN 2,923,795

MULTI-POLE CIRCUIT BREAKERS Filed July 3, 1957 3 Sheets-Sheet 2 INVENTOR wizyw Feb. 2, 1960 P. s. MARTIN 2,923,795

MULTI-POLE CIRCUIT BREAKERS Filed July 3, 1957 3 Sheets-Sheet 3 INVENTOR "m m "i T 1 3; 3 58 wk T 5 8 40 0* States Patent 2,923,795 MULTI-POLE CIRCUIT BREAKERS Paul S. Martin, Flushing, N.Y., assignor to Federal Pacific Electric Company, a corporation of Delaware Application July 3, 1957, Serial No. 669,881 17 Claims. (Cl. 200-116) The present invention relates to circuit breakers of the multi-pole type.

An object of the present invention is to provide a novel tripping mechanism for multi-pole circuit breakers to trip the entire circuit breaker in response to an overload in any one of the poles. More specifically it is an object of the present invention to provide a novel tripping mechanism for multi-pole circuit breakers in which each pole has it: own operating mechanism for opening and closing the circuit breaker and in which each pole has a current-responsive control element.

Multi-pole circuit breakers include a common operator for closing and opening the circuit breaker and suitable mechanisms for transmitting the closing drive from the common operator to the respective movable contacts. A feature of the present invention resides in the provision of a releasable contact-operating toggle in the connection between the manual operator and the movable contact members, which toggle not only furnishes drive for the movable contact members in the closing direction but in addition the toggle of a tripped pole provides drive to the toggles of the other poles to buckle them and permit opening of the other poles. In the illustrative embodiment described below in detail, each pole includes an overload release means in addition to its toggle. The locked toggle of a tripped pole, whose overload release means has operated, is bodily shifted in a way to buckle the toggles of the other poles, whose overload means remain latched.

The invention has particular application to a form of circuit breaker in which a movable contact member of each pole carries both a current-responsive element and an actuator that is latched by the current-responsive element. The contact member and the actuator latched by the current-responsive element act as a unit that is driven in the closing direction by an operating handle common to all the poles. Such circuit breakers are shown, for example, in Patent No. 2,700,713 issued January 25, 1955 to T. M. Cole et al. and Patent No. 2,681,396 issued June 15, 1954 to T. M. Cole et al. The adaptation of such circuit breakers to operation for simultaneous tripping of two poles is shown in Patent No. 2,662,- 949 issued to Christensen et al. on December 15, 1953. As will be seen, the present invention is a novel tripping arrangement useful for two-pole circuit breakers of the type in the patents to T. M. Cole et al., but it is equally applicable to function for three and more poles.

In the circuit breakers of the patents mentioned above, the current responsive element that acts as a latch is a bimetal, that is deflected by heating due to overload current, and by magnetic action in the case of severe overloads due, for example, to short circuits. The current-responsive latch may alternatively be a supplemental mechanical latch operated by a bimetal or by an electromagnet or both.

The circuit breaker in the illustrative disclosure is tripfree, that is, capable of opening even though the manual operator might be held in its closed position. Furthermore, the disclosed circuit breaker operating handle is optionally returned part-way or all the way toward its off position, after being tripped, so as to be either trip-indicating or self-resetting as may be preferred.

A further object of the invention resides in the use of a trip bar for a multi-pole circuit breaker in a novel arrangement in which the current-responsive means of each pole is not mechanically loaded by the combined latch friction of all the poles. In some known multipole circuit breakers using a trip bar, each overloaded current bimetal pushes the trip bar in the releasing direction. One overloaded pole will therefore trip the breaker at a higher value of current than would be effective if two or three overloaded bimetals of multiple poles were acting on the trip bar concurrently.

A still further object of the invention is to provide for virtually simultaneous contact parting of the multiple poles in a novel arrangement, accomplished herein by initial motion of the released element that acts to buckle the toggles of the unreleased poles. Each pole includes a spring providing so-called over-travel of the contacts, that is, over-travel of the contact-operating mechanism after actual engagement of the contacts during a closing operation. In the illustrative embodiment, the mecha? nism of a tripped pole operates the released element during reverse action of the over-travel spring that keeps the contacts of a tripped pole closed while the toggles of the other poles are buckled.

The nature of the invention and its further objects and features of novelty will be better appreciated from the following detailed description of the illustrative embodiment which is shown in the accompanying drawings forming part of this disclosure. In the drawings:

Figs. 1 to 4 are the side views of an end pole of a three-pole circuit breaker with the parts thereof in vanious operative positions, the cover being removed and certain parts being shown in fragmentary section. In Fig. 1 the mechanism is shown in the contacts-closed position; in Fig. 2 the mechanism is shown in its open position, ready for reclosing; in Fig. 3 the parts are shown at the instant of overload release; and Fig. 4 is a view of the mechanism of Fig. 1 in the position it occupies after overload release and opening of the contacts, with the operating handle of the circuit breaker manually held in its on position, 'during overload release.

Figs. 5 and 6 are side views of the center pole of the illustrative three-pole circuit breaker as the parts thereof appear in the different phases of operation corresponding to Figs. 3 and 4 respectively.

Fig. 7 is a fragmentary transverse section of the illustrative multi-pole circuit breaker along the line 7-7.

of Fig. 1.

Fig. 8 is a plan view of a trip bar looking upward in Fig. 7.

Fig. 9 is a cross-sectional view of the trip bar in Fig. 8 along the line 9-9 therein.

Fig. 10 is an end view of'the trip bar in Fig. 8.

Figures 11, 12 and 13 are successive cross-sections of the trip bar in Fig. 8 along the lines 1111, 12-12, and 1313 in Fig. 8.

Figs. l4, 15, 16 are enlarged fragmentary cross-sectional views of two of the elements of Figs. 1 to 4 in various operational configurations thereof.

Fig. 17 is a fragmentary cross-section of a portion of the mechanism in Fig. 4 along the line 1717 therein.

Referring first to Fig. 7 there is shown a fragmentary cross-section of a three-pole circuit breaker embodying I features of the invention. Three cavities 10, 12 and 14 of the circuit breaker are shown. Cavity 10 is formed" formed between casing walls 24 and 26. Naturally walls 18 and 20 may be made as one piece, which is also true of walls 22 and 24. Each eavity 10, 12 and 14 contains a completelcircuit-breaker mechanism, including apair of co tacts. a con -op at ng l nka e d a rl d release means; anda novel common release means forms part of each pole of the three-pole circuit breaker, as. will be seen in connection with the discussion of Figs. 1 to 6 inclusive below. A common operator for all three poles is provided, including molded members 28, 3t and 32 of insulation having square holesreceiving metal shaft 34, which is of square cross-section, Members 28 and 32 are journaled in the outside casing walls 16 and 26, respectively, and each member 28, 30 and 32 is guided, w h r spe t to t a l, position along h f y h arin s in vthe e pec i e Casi:. s-w pairs. Ire- 20+ and 2 6 betwe n. h eh lmtz... n a b r. is c nfine Member 30 has a handle. 30a projecting externally or the cas n o be perated man a ly for opening, a d c os ng cir uit breakera end members as and or the com manua op at r'ha ed pending ed. p ns 28 nd 2a (see Figs. 7 and 8 Members 28 and 32 contain U- shaped metal members 36, which members are wholly concealed within those molded members except for a projecting pivot portion 36a. Common trip bar 38 for all the poles (Figs. 7-11) has apair of end openings 40 which receive portions 364 of the composite manual oper or Trip bar 38 has three bearing apertures for three U- shaped wire members 42. In Fig.7 these members 42 are designated 42a, 42b and 420 to distinguish the three poles, and these designations are used in Figs. 1-4, and in and 6, respectively. When the composite member 2830 32 -34 is oscillated by manipulation oi handle 30a, U shaPed members 36' operate the common trip bar 38 and, acting through members 42, operate the separate mechanisms of the three poles for opening and closing the contacts, and in resetting, as will be seen.

The mechanism of each pole is the same asthe mechanism for each of the other poles, to the extent that all are operated by respective members 42, being in turn operated by the common trip bar 38 and the composite manual member described. One of the mechanisms appears in Figs. 1 to 4 and another, duplicate mechanism, is shown in Figs, 5 and 6. i

In Figs. 1 to 4 there shown a first terminal 44 rigidly carrying a stationary contact 46. Movable contact 48 engages contact 46 when the circuit breaker is closed, movable contact 48 being supported on elongated contact-carrying arm 50 that is pivoted near its center on a transverse coil spring 52 (see Fig. 17). Carried on pivot 54 in an insulating bearing (not shown) at the end of contact arm 50 remote from contact 48, is an actuator 56- having a bearing58 which receives the U-shaped wire member 42a mentioned above. An ambient temperature compensating bimetal 60 has its upper end curved about in Fig. 1. An electrical circuit may be traced through the circuit breaker from terminal 44 across contacts 46 and 48, into moving contact carrying arm 50, via bimetal 62 and braid 64 to terminal 66. There is no current-bypass path bridging bimetal 62 by virtue of the insulated pivot 54 which is more fully disclosed in Patent 2,647,186, issued July 28, 1953, to Thomas M. Cole.

To provide tor snap-closing operation, V-shaped member 68 is rockably' carried on contact arm 56. Manual operating member 28 has a projection 70, and between this projection andthe V-shaped member 68there is a compression spring 72, which biases movable contact member in the opening direction. With handle 30a in the position illustrated that handle-is locked in its on position (as shown in Fig. 1) by a locking toggle consisting of one part 3628 and another part 38-42 whose knee 36a is overset. The angle of overset of this locking toggle is limited by. handle engagement with the enclosure. The" circuit breaker is shown off or open in Fig, 2. in that position, member 68 is rocked counterclQQkWise by compression spring. 72 and handle 3042 as well as all other parts of the composite manual operator 28, 38, 32 and 34 are biased in their open direction by springs 72. Contact arm 50 is also biased open" by spring 72.

The operation of themechanism thus far described is as follows. During the closing stroke, of handle 3%, the elements named a locking toggle function as an operating or a driving linkage. The composite handle 28 30-3234 operates trip, bar 38 from the position in Fig. 2 toward the right, bodily, and this in turn pushes wire elements 42. to the right, urging actuator 5668 clockwise. until the lower tip of bimetal engages the tip ofbimetal 62. After this point, further operation of the handle, the tripv bar 38 and element 42 (element in-42a in Figs. 1 -4.) drives the latched triangular assembly 58, 5660, and, 62 clockwise about pivot 52 until the lefthand arm of element 68 is arrested by shoulder '74. Continued operation of handle 30a cannot drive contact 48 any further, but is efiective to displace member 50 and to bias spring 52 into its downward sagging'condition illustrated in. Fig. 17. Before handle 30a reaches its full on position, handle portion 70 shifts spring '72v to-rock V.-shape'd member 68- to the right and out of engagement With shoulder 74. At that instant, contact bearing 58 and its lower end is slidably guided by a formed portion of member 56 so that the lower tip of bimetal 60 is projected to a variable extent in dependence on the ambient temperature.

Acurrentresponsive bimetal 62 is joined to contact carrying arm 50 at the left-hand end and its free'right hand end (Figs. 1-4) current responsivebimetal 62 normally acts as an abutment for the lower tip of ambient temperature compensating bimetal 60*, A flexible metal braid 64' has one end joined to bimetal 62 and its opposite end is joined to terminal 66, of a form suitable for panelboard plug-in installation as disclosed in Patent 2,647,225, sued a uar .9 1 t C l e a1. Am i nttem- Pa re mren atina bimetal. .0 is mo fu dan ed ndis aim din pp ca on. 5 1 ti ed J 1y 35 3. y Tho s M. C l imw at nt N 2.80 21. issued=August 20, 1957. i 1 v The end pole of thecircuit'breaker is shown closed,

I member 50 is quickly propelled clockwise to close the contacts. Spring 72 is much softer than spring 52 and the latter provides this. snap-acting contact-closing impetus.

Spring 52falso. provides for over-travel. it will be understood that the contacts 46, 48 must engage each other when the circuit breaker is closed and this overtravelis provided for insuring such; engagement despite erosion of some of the contact material during use and despite usualv dimensional variations of the assembled parts. in. production; With the mechanism as shown in Fig. 1, spring 52 is stressedandbiases the contacts closed; and they contacts remain closed during the initial part of the opening operation until this stress'is released. The operatinglinkage hasan over-travel in the closing direction which corresponds to. that part of the opening stroke during which the contacts remain closed.

Tripping of'the circuit breaker for automatic opening inevent of over load may result from heating of bimetal 62 which defiects'its free right-hand extremity downward. Additionally there is provided a soft iron core 76 which is united tomember 50 at its left-hand end, at the same place where member 62 is secured. In the event of a heavy surge ofcurrent through bimetal 62, the magnetic field of this current inthreading through core 76, produces a force of attraction which deflects the free end of himetal 62 downward so as to eifect releaseof the circuit breaker. Additional arrangements for effecting overcurrent release of circuit breakers of comparable construction are-shown in application S.N. 353,741. filed.

May 8, 1953, and application S.N. 590,712 filed June 11, 1956 by Thomas M. Cole.

In the event of an overload and downward deflection of the latch end of bimetal 62 as a result of such overload, actuator 56-60 is released, and is referred to at times as a releasable member, bimetal 62 acting as a latch. Upon freeing of the releasable member 56-60, coil spring pivot 52 very quickly snaps straight and drives member 50 counterclockwise about the engaged contacts 46, 48 as a fulcrum. In so doing member 50 lifts members 56 and 42a. Trip bar 38 has a portion 38awhich rests on member 42a and by virtue of this engagement, the lifting of member 56 upon tripping also lifts trip bar 38 so as to swing that trip bar counterclockwise about pivot portion 36a of wire member 36. As will be seen below, the counterclockwise operation of member 38 as just described is effective to trip the other poles of the circuit breaker. This tripping operation of the related poles, other than this pole which has been considered released by an overload, is effective while the contacts of the overloaded pole remain closed. Members 38 and 42a constitute a release toggle which is locked or straight (rather than buckled), and the toggle of the overload-release pole remains in this condition during the release of the other poles.

In Figs. 1 to 4 as described above there is a series of phases of operation of one single pole of the multi-pole circuit breaker, presumed to be overloaded. Figs. 1, 2 and 3 have been described as representing the circuit breaker closed, open, and at the instant of tripping. Fig. 4 illustrates a further phase of the circuit breaker operation that might occur. This illustrated condition is the result of holding the circuit breaker closed against a short circuit, as may arise when the circuit breaker is closed on a short circuit. Under such conditions, handle 30a is inevitably held closed after overload release is effective. Release of the other poles (as described below) lifts trip bar 38 and operates elements 38 and 42a relative to each other, to assume the configuration illustrated in Fig. 4. As seen in Fig. 4, the contacts are fully open even though the handle is in its on position. When the'handle is thereafter released, spring 70 is effective to bias the handle clockwise toward the open position. If some frictional detent is present providing interference against the free return of the handle to the full oil position, the handle will be arrested at an intermediate position, to indicate the tripped condition of the circuit breaker. If there is no such obstruction, the composite operating member 28, 30, 32 and 34 will be returned to its full off position after the person operating the circuit breaker releases handle 30a. The circuit breaker will then be in reset and in its normal off condition. In the event that a frictional obstruction is provided, the handle can be manually reset from its intermediate trip-indicating position into the off position in order to reset actuator 56-60 to the required position for reclosing the contacts, as represented in Fig. 2.

The toggles consisting of trip bar 38 and wire elements 42 may assume various configurations, as mentioned above, either buckled as in Fig. 6, or straight and locked as in Fig. 1. At the start of a closing stroke of operation of the handle 30a, it is desirable that the toggle con sisting of elements 38 and 42a, 38 and 42b and 38 and 420, should in each instance be locked. For the purpose of assuring that this will be the case, trip bar 38 has a.

doubleheaded rivet slidably received therein (Fig. 13) with a compression coil spring 80 between the upper head of that rivet and the trip bar 38. When the handle 30a is in the off position (Fig. 2) rivet 78 and compression spring 80 bear against element 30 of the composite operator structure so as to bias trip bar 38 clockwise about its supporting pivots 36 and thereby press portions 38a against each of the toggle members 42a, 42b, and 42c.

In the condition of the release toggle 38-42a shown in Fig. 2, there is an overset angle between the line-ofcenters of member 42a compared to the line-of-centers of bearing 58 and pivot portions 36a of member 36, and the release toggle is locked or straight as opposed to buckled (Figs. 4 and 6 for example).

When the handle is rotated from its off position illustrated in Fig. 2 to its on position illustrated in Fig. 1, it rotates through an angle of approximately 60. Member 36a which is a round shaft projecting into opening 40 of the trip bar 38 also rotates through this same number of degrees. If opening 40 were a simple round bearing for receiving portion 36a, and if appreciable friction were present, then there would be a torque tending to rotate member 38 counterclockwise with handle 30a as the handle is operated toward the on" position. This counterclockwise rotation is in the direction to buckle the release toggle, which is to remain straight or locked during the on operating stroke.

For avoiding the frictional torque tending to buckle the release toggle, opening 40 is formed as an elongated slot and provides a bearing surface over which the pivot portion 361: of element 36 may roll. The rolling travel of portion 36a from the off position to the on position during which it rolls along one wall of opening 40 is illustrated in Figs. 14, 15 and 16. In these figures, the pivot of composite manual operator 28, 30, 32 and 34 is diagrammatically represented by the numeral 82. Fig. 14 shows the relationship of members 38 and the line-ofcenters 82-36a in the off condition of the circuit breaker (Fig. 2). Fig. 16 shows the relationship of trip bar 38 to the line-of-centers 82-36a in the on condition of the circuit breaker (Fig. 1). Fig. 15 represents an intermediate operative position between the extremes of Figs. 14 and 16. During its advance to the right in these figures, element 36a is seen to rotate counterclockwise through an angle of about 60. At the same time member 38 is seen to rotate clockwise through an angle of about 60. The relative rotation is thus about 120".

At the start of the on stroke, element 36a presses against the right-hand wall of elongated opening 40 in trip-bar 38. During the on stroke and incidental to the rotation of axis 82-38a (corresponding to handle rotation) relative to the trip bar 38 that also rotates through a substantial angle, element 36a rolls along the right-hand wall of slot or elongated opening 40. This rolling action eliminates risk of troublesom friction that might otherwise develop between element 36a and trip bar 38, and thereby eliminates the possibility of friction buckling the release toggles 38-42a or 38-42b or 38- 420. The slot 40 may thus be considered to be a frictionless bearing for the pivot 36a. The walls 40a (Figs. 14-16) of slots 40 against which pivot pins or shafts 36a press during rolling travel are formed as an are about pivots 58. In this way, actuating thrust is maintained in line with the end pivots of toggle(s) 38-42.

During the advance of these parts from the off to the on position, thecenter of element 36a which is an end pivot of the release toggle, shifts in relation to the lines established by the extremities of elements 42a, 42b, and 42c. At the outset, the release toggle 38-42 is considerably over-set so as to have an angle of about 20 between the line joining element 36a and bearing 58 and the line established by element 42. At the end of the on stroke, there is still an over-set angle of about 6". This angle, while apparently somewhat critical, is easily maintained in manufacture because it is established almost entirely by the shape of the trip bar.

It is important if this rolling action is to occur consistently that element 36a should be reliably positioned initially at the top of the elongated slot 40. Otherwise the rolling action would not occur through the lengths of strokes and the degree of relative rotation described. The rivet 78 and its coil compression spring 80 previously described is effective not only to straighten the release toggle 38-42 but additionally to bias the common trip garded as asingle element.

of each member-42a, 42b, and 42c, may be termed the knee of the release toggle which is over-set or straight or locked during the oif-to-on operating stroke of handle 30a. During this closing stroke of operation, each release toggle 38-42 is a driving link which may be re- This driving element interconnects the composite operating handle and the separate 1 actuators '56. Thrust is transmitted from the composite handle by way of each locked release toggle 38-42 to the related actuator 56 which applies pressure against the end of bimetal 62; and after engagement of the actuator 56-60 with bimetal 62, the element 56-60 actuates the contact bearing arm to effect closing of the contacts.

Notably each pole includes its own actuator 5668 that is releaseable by deflection of the current-responsive element 62. The pressure of each element 566'0 against the current-responsive element 62 is the latch pressure, a factor that partly determines the current level at which tripping occurs. 7 In this three-pole circuit breaker, each pole includes its own releasable current-responsive latch 62 and the latch pressure of each pole is not appreciably influenced by the latch pressure developed at the other poles. In order for each current-responsive bimetal 62 to deflect, it is only necessary to overcome its individual latch pressure. I

With the above background, multipole operation may be explained. Referring to Figs. 1, 2, 3 and 4, it is seen that the casing wall 18 is provided with an opening 84, and (Fig. 7) an aligned opening is also provided in each internal wall 20, 22 and 24 of the enclosure. These aligned openings provide the space for the composite actuating member 28, 30, 32, 34 and for the common trip bar 38 which extends across all of the three poles. Figs. 1-4 illustrate the effect of an over-load released pole on trip bar 38. Figs. 5 and 6 illustrate how the trip bar functions in a pole that is not overloaded when (Fig.3) one of the poles is overloaded and released by its bimetal. Fig. 3 illustrates how common trip bar 38 is swung counterclockwise through a limited angle in response to release of the actuator 5'6*60 of that pole. This counterclockwise swing of member 38 is seen in Fig. 5 to cause portion 38a of the trip bar 38 to be lifted away from element 42b of the center pole, that is, to trip the release toggle of the center pole. "In this condition the thrust developed between member 56- and ele-.

ment 36a of that center pole causes release toggle 38- 42b to buckle and allow the contact arm 50 of the nonoverloaded pole to operate in a contact-opening stroke. This operation takes place even though the handle is held on as illustrated in Fig. 6. If the handle is al lowed to return to its off position under the influence of the compression spring 72 of that mechanism, then the mechanism returns to the off position that is normal as illustrated in Fig. 2.

In Figs. 8 to 12 inclusive there are shown a number of views of the trip bar which is formed in a manner to facilitate manufacture and assembly. Trip bar 38 is formed of one piece as a molded insulator. At the lefthand side of Fig. 8 portion 28a of the operating element 28 is shown with its wire member 36 inserted into the opening 40 at one end of the trip bar 38. At the righthand extremity of Fig. 8 the other element 36a carried by element 32, 32a, is in condition for insertion into the opposite opening 40.

At the left-hand extremity of Fig. 8, therelease toggle element 42a is shown in dotted lines before insertion; and from this position it is advanced axially into its bearing in element 38 and then it is rotated 90 to assume the full-line position illustrated. This motion is perhaps better illustrated ir 'Fig. 9. Elements 42b and 42c are inserted similarly, a recess 86 being provided to accommodate this assembly operation. At the time of insertion, each element 42 is advantageously part of the sub-assembly 50-56'-60- -62. The leg of each element 42 that-extends through bearing 58 in member 56 is swaged with a head as shown in Fig. 7 to prevent accidental removal in use.

The three bearings for the respective toggle members 42a, 42b and 420 in trip bar 38 are formed by molding openings into the trip bar from the opposite sides of the trip bar. Thus a'pair of openings 88 (Fig. 9) are molded into oneface of the trip bar and another opening 90 is ,molded into the opposite face of the trip bar, these openings 88 and 90 being deep enough to provide a continuous endwisepassage or bearing for receiving one leg of the element 42a. Similar complementing openings are formed for providing respective bearings for one leg of each element 42b and 420 in common trip bar 38. Similar axially extending bearings are provided in member 38 by openings molded into member 38 from the opposite sides thereof in order to provide respective elongated bearings 40 for elments 36a of the composite actuator.

The operation of the entire circuit breaker may now be summarized as follows:

The circuit breaker consists of three'virtually identical poles each having its own operating mechanism and each having its own overload release device. In addition, each of the poles has a release toggle 38-42, with one of the release toggle elements taking the form of a common trip bar extending across all of the poles.

When the circuit breaker is fully open, as illustrated in Fig. 2, the circuit breaker is in condition for being closed. In that condition, each of the release toggles 38-42 is locked or over-set, this configuration being assured by rivet 78 and spring 80 bearing against element 30 of the composite manual actuator. Also, element 36a at each end of trip bar 38 is biased by rivet 78 and spring 80 to the upper extremity of the elongated opening 40 foirned in each end of the trip bar-38. Initial'operation of handle 30a counterclockwise in Fig. 2 pushes actuator 5 6'6 into engagement with the end of current responsive" bimetal 62. Thereafter continued thrust of the handle 30a in the contact-closing direction tothe left in Fig. 2 causes the elements 5856+), and 62 to pivot as a unit about spring 52. Obstruction element 68 engages a shoulder 74 formed in the casing, which arrests the advance of moving contact arm before the contacts engaged. Continued drive of handle 30a in the closing direction stresses spring 52 which assumes the sagging configuration in Fig. 17. Near the end of the on stroke of handle 38a, handle projection 70 operates spring 72 against the right-hand arm of V-shaped'member 68 and shifts that member out of its obstructing position. Spring 52 is then effective to snap the contacts closed, this spring being stiffer than contact opening spring 72 which opposes such closing operation. When handle 30a completes its on stroke, the locking toggle which may also be called an actuating toggle, consisting of the composite operating elements 2830-3234-36 as one element and elements 38-42 as the other element, becomes over-set and, locks each pole of the. circuit breaker closed, against the opening bias of the several springs 72. e

In the event of a sudden overload in any one of the poles, bimetal 62 is deflected downward by attraction to the core 76 and actuator 56-60 is released. A more gradual overload causes bimetal 62 to deflect out of engagement with actuator 56-60 to release that overloaded pole. When this occurs, spring pivot 52 in its initially sagging condition straightens quickly and lifts actuator 56 so as to assume, the operational position of Fig. 3 in which the contacts are stillclosed. This. action swings trip bar 38. counterclockwise to a sufficient extent to buckle the toggles of the adjoining poles, as illustrated in Fig. 5'. All of the springs 72 are then effective to 9, drive the respective contact-carrying arms 50 in the opening direction.-

During the initial phase of operation represented in Figs. 3 and 5, the spring pivot 52 functions (as previously described) to provide over-travel of the contact closing mechanism and thereby to insure closing of the contacts. During the reverse operation, as an incident of the release of an overloaded pole, the over-travel spring is effective to keep the contacts closed during the release of all the release toggles 3842 of the untripped poles, with the result that springs '72 drive all of the poles open virtually simultaneously.

The circuit breaker is trip-free, in the sense that the contacts of the overloaded pole as well as the contacts of the poles tripped by the common trip bar are free to open even though the handle 30a is held in its on position. This condition is illustrated in Figs. 4 and 6. When the handle 30a returns to its off position, either by being returned by springs 72 or by being manipulated into that position any actuator 56-60 that may have swung to the position in Fig. 4 is returned to the position of Fig. 2 by the tension developed in elements 38 and 42 between elements 36a of the composite operator of the circuit breaker and the bearing 58 of each actuator 5660. The actuators 5660 of the non-overloaded tripped poles remain in the condition required for reclosing of the circuit breaker.

Springs 72 act on contact arms 50 at a very prominent distance from the respective pivots of the contact arms 50'. Therefore the opening force applied to the moving contact arms 50 is reliable and the contacts return to their open position under proper circumstances. However the action of springs 72 against the three elements 28, 3t) and 32 is directed relatively close to the pivotal axis of those elements and in consequence handle 30a will be returned toward the off position only to the extent permitted by a frictional trip-indicating obstruction that may be provided. Under such conditions the partly returned handle 30a is manually reset to off before the circuit breaker is to be reclosed. If the circuit breaker casing is designed for full clearance, then springs 72 will return the composite operator 28303234-36 and the elements operated thereby to the full off position in Fig. 2.

There has been given above the detailed description of an exemplary practical application of the invention in its various aspects, but those skilled in the art will readily appreciate the possibilities of modification and varied application of its novel features; and therefore it is appropriate that the invention should be broadly construed, consistent with its full spirit and scope.

What is claimed is:

1. A multi-pole circuit breaker having a pair of separable contacts in each of plural companion poles, a common manual operator for all the poles thereof, a tripfree contact-operating mechanism in each pole connected to said manual operator for operating one of said contacts of that pole and thus opening and closing the circuit breaker manually, the contact-operating mechanism of each pole including a current-responsive latch and a contact-operating means controlled by the latch of that pole, the contact-operating means of each pole including release means additional to said latch and operable to release the contact-operating means of that pole while the latch thereof remains latched, said additional release means of each pole being connected to the contactoperating means of each companion pole at least in the closed condition of the circuit breaker, and the releaseable means of each latched pole being releaseable by the connected contact-operating means of any unlatched companion pole during initial operation thereof after being unlatched.

2. A multi-pole circuit breaker having a pair of separable contacts in each of plural companion poles, a common manual operator for all the poles thereof, a tripfree contact-operating mechanism in each po'le connected to said manual operator for operating one of said contacts of that pole and thus opening and closing the circuit breaker manually, the contact-operating mechanism of each pole including a current-responsive latch and a contact-operating means controlled by the current-responsive latch of that pole, the contact operating mechanism of each pole including release means additional to said current-responsive latch and operable to release that pole while the latch thereof remains latched, each pole including resilient -means affording an overtravel of the manual operator in the contact-closing direction following initial contact engagement, said additional release means of each pole being connected to the contact-operating means of each companion pole at least in the closed condition of the circuit breaker, and the releaseable means of each latched pole being released by the connected contact-operating means of any unlatched pole during the overtravel portion of the operation thereof in the contact-opening direction. I

3. A multi-pole circuit breaker having a pair of separable contacts in each of plural companion poles, a common operator for all of the poles thereof, a trip-free contactoperating mechanism in each pole connected to said manual operator for operating one of said contacts of that pole and thus opening and closing the circuit breaker manually, the contact-operating mechanism of each pole including a current-responsive latch effective to hold the contacts closed or to trip the operating mechanism thereof for automatic release of the contacts of that pole in response to an overload, the contact-operating means of each pole including release means additional to said latch and operable to release the contact-operating means of that pole while the latch thereof remains latched, said additional release means of each pole being connected to the release means of each companion pole at least in the closed condition of the circuit breaker, and the releaseable means of an unlatched pole being displaced in its unreleased condition as an incident of the initial operation of the contact-operating means of that pole, said displacement being in the direction to release the releasable means of any companion pole that remains latched.

4. A multi-pole circuit breaker having a pair of separable contacts in each of plural companion poles, a common manual operator for all the poles thereof, a tripfree contact-operating mechanism in each pole connected to said manual operator for operating one of said contacts of that pole and thus opening and closing the circuit breaker manually, the contact operating mechanism of each pole including a current-responsive latch and contactoperating means controlled by the current-responsive latch of that pole for normally holding the contacts closed and for automatically releasing the contacts of that pole in response to an overload, the contact operating means of each pole including release means additional to said current-responsive latch and operable to release that pole while the latch thereof remains latched, each pole including resilient means affording an overtravel of the manual operator in the contact-closing direction following initial contact engagement, said additional release means of each pole being connected to the additional release means of each companion pole at least in the closed condition of the circuit breaker, and the additional releaseable means being arranged to be displaced in its unreleased condition during the initial contact-opening operation of the contact-operating means of an unlatched pole, the releaseable means of an unlatched pole that is displaced as an incident of the operation of the contact-operating means thereof being etfective to release the releaseable means of any latched pole during the overtravel portion of the operation of the unlatched pole in the contactopening direction.

5. A multipole circuit breaker having a common operator, a pair of contacts in each pole, an individual mechanism for each pole operated by said common operator to operate the. contacts open and closed, each said mechanism including a releasable toggle including a pair of links pivoted together and locked when overset, each toggle when overset acting as a drive linkin such mechanism, each pole including an individual current responsive latch effective to release the mechanism thereof for automatic opening of its contacts in response to an overload despite the locked condition of the toggle there: of, one link or" each of said toggles being connected to the corresponding link of the toggle of each other pole oi the multipole circuit breaker inthe closed condition thereof, and the mechanism of an overload-released pole carrying its locked toggle in the direction to release the toggle in any pole not released by an overload.

6. A multipole circuit breaker having a common'operato-r, a pair of contacts in each pole, an individual mechanism for each pole operated by said common operator to operate the contacts open and closed, each said mechanism including a releasable toggle as a drive link therein, each pole including individual current responsive means efiective to release the mechanism thereof for opening of its contacts in response to an overload, the releasable toggle of each pole remaining locked initially after release of its mechanism by itscu-rrent-responsive means, said toggles each having a link connected to the corresponding link of the toggle of each other pole, the initial contact-opening operation of the operating mechanism of an overload-released pole driving its locked toggle and thereby carrying the interconnected toggle links of all thepoles in the direction to buckle the toggle of any pole not released by an overload.

7. A multipole circuit breaker including a pairof contacts for each pole, mechanism for holding each pair of.

been closed, and an in- 7 contacts closed after having dividual current responsive latch for each pole ettective for releasing the holding mechanism of its related pole in response to an overload, each pole including a releasable toggle additional to said current responsive release latch, said toggle'forming part of said mechanism, said toggles having first and second links and said first links being interconnected for conjoint action, the toggle of an overload-released pole initially remaining a locked unit and being shifted bodily as an incident to the releasing operation of said contact-holding mechanism to shift all said first toggle links in the direction to buckle the toggle of any unreleased mechanism.

8. A multipole circuit breaker including a common operating handle, a pair of contacts for each pole of the circuit breaker, a movable contact member for each pole to operate one of said contacts, a current-responsive latch for each pole, an actuator for each pole pivotally carried by each movable contact member and normally latched by said current-responsive element when the circuit breaker is closed, and each pole having a toggle forming a link between said common operating handle and said actuators, respectively, said toggle including one member individual to each pole and a second member extending across all of the poles, said second member being carried by said operating handle and constrained thereby to remain parallel to the pivotal axes of said actuators.

9. A multipole circuit breaker including a common pivoted operating handle, a pair of contacts for each pole of the circuit breaker, a movable contact member to operate one of said contacts, a current-responsive latch carried by each movable contact member, an actuator pivoted to each movable contact member and normally latched by said current-responsive element when the circuit breaker is closed, and a toggle forming a link be-. tween said common operating handle and said actuators, respectively, said toggle including one member individual to each pole and a second member extending across all of the poles and constrained to remain substantially parallel to the pivotal axis of the common operating handle, the mechanism for operating the movable contact member of any one pole being releasable by its current-responsive means and said mechanism being effective upon release to shift said one member of the released pole and to shift said second member of the released pole as a unit therewith into releasing configuration with respect to the toggle of any companion pole not released by an overload.

10. A multipole circuit breaker including a common pivoted operating handle, a pair of contacts for each pole of the circuit breaker, a movable contact member to operate one of said contacts, a current-responsive latch carried by each movable contact member, an actuator pivoted to each movable contact member and normally latched by said current-responsive element when the circuit breaker is closed, and a toggle forming a link between said common operating handle and said actuators, respectively, said toggle including one member individual to each pole and a second member extending across all of the poles and constrained to remain substantially parallel to the pivotal axis of the common operating handle, the mechanism for operating the movable contact member of any one pole being releasable by its current-responsive means and said mechanism being effective upon release to shift saidone member of the released pole and to shift said second member of the released pole as a unit therewith into releasing configuration with respect to the toggle of any companion pole not released by an overload, each pole including resilient overtravel means, and the toggles being proportioned relative to the overtravel means so that the toggle of each companion pole not released by an overload is released during the release of the resilient overtravel means of an overload- 7 released pole.

s end thereof remote from its contact, each actuator being in latching engagement with'its related current-responsive latch when the circuit breaker is closed, and a multipole toggle interconnecting said common operator and the actuators of said poles, said toggle including one toggle link individual to each pole and pivoted to the actuator thereof and said toggle including a bar constituting a second toggle link interconnecting said common operator and said individual toggle links and compelling the knees of the multipole toggle to move in unison, said toggle being normally locked when the circuit breaker is closed, spring bias means tending to hold said actuator against its related current responsive latch when the circuit breaker is closed and to move. said actuator when released by said current responsive latch, the released one of said actuators being thereby effective to bodily shift its individual link and said second link in the direction to release the toggle in each other contact operating mechanism.

12. A multipole circuit breaker in accordance with claim ll, wherein each pole includes spring means providing for overtravel of the common operator in the contact closing direction beyond the point at which the con tacts theoretically may make initial contact and wherein the toggles are proportioned so that buckling thereof is efiected in any non-overloaded pole 'after'current-responsive release of an overloaded pole while the overtravel spring means maintains engagement of the contacts'of the overloaded pole.

13. A toggle mechanism including a first toggle link having first end bearing means, multiple parallel toggle links pivoted to said first toggle link at respective coaxial points constituting knees of the toggle and said parallel links having coaxial second end bearing means at the side of said knee remote from said first end bearing means, said links embodying locking means limiting the relative displacement of said knee in one direction relative to the line-of-centers through both said end bearing means, individual means to apply thrust to said toggle links when in locked configuration, and means to displace said first toggle link and one of said parallel toggle links in locked configuration about said first end bearing means in the direction to shift the toggle knee of each other parallel link in the toggle-buckling direction.

14. A multipole circuit breaker including a common operator, plural independently operable contact members, individual overload release means for said contact members to operate the contact member of an overloaded pole automatically, and a toggle mechanism operatively connecting the common operator and said contact member for automatically operating the companion poles in response to initial operation of an overloaded pole, said toggle including a first toggle link having first end bearing means, multiple parallel toggle links pivoted to said first toggle link at respective coaxial points constituting knees of the toggle and said parallel links having coaxial second end bearing means at the side of said knee remote from said first end bearing means, said links embodying locking means limiting the relative displacement of said knee in one direction relative to the line-of-centers through both said end bearing means, individual means to apply thrust to said toggle links when in locked configuration, and means to displace said first toggle link and one of said parallel toggle links in locked configuration about 15. A three-pole circuit breaker, including in each pole a pair of separable contacts, a contact member carryovertravel stroke of said overcurrent released pole to break the drive connection of any unreleased pole for trip-free opening of the contacts thereof.

16. A three-pole circuit breaker including in each pole thereof a current-responsive latch, companion contacts and mechanism for closing and holding said companion contacts closed and for opening the contacts under control of said latch, said mechanism including in each pole a toggle that is in overset condition both when its related companion contacts are closed and during the initial portion of the contact-opening operation of said mechanism following release thereof by said latch, the toggles of all said poles having one link of each rigidly connected to the corresponding link of each other pole and the toggle of an over-current released pole being arranged to be operated in its overset condition in the direction to drive said connected links in the direction to release the toggle of any companion pole whose current-responsive latch has not been released.

17. A three-pole circuit breaker including in each pole thereof a companion pair of contacts, drive mechanism abling operation of the drive mechanism in the closing direction beyond the initial contact engagement thereby building up contact-pressure and stress in the over-travel spring, an overcurrent release means in each pole and an additional release means in each pole, the additional means of all the poles being operable individually and in any combination for releasing their respective drive mechanisms, a common operating handle for the drive mechanisms of all the poles, and a common connection extending to said additional release means of all the poles and operated by the over-travel spring of an over-currentreleased pole to effect release of the additional release means of any pole whose over-current release means remains unreleased.

References Cited in the file of this patent UNITED STATES PATENTS 

